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List: xen-cvs
Subject: [xen staging] xenstored: send an evtchn notification on introduce_domain
From: patchbot () xen ! org
Date: 2022-05-24 23:22:45
Message-ID: E1ntdrR-0003UO-3q () xenbits ! xenproject ! org
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commit fc2b57c9af462d67df871b080c0897156a616b7d
Author: Luca Miccio <lucmiccio@gmail.com>
AuthorDate: Fri May 13 14:07:28 2022 -0700
Commit: Stefano Stabellini <stefano.stabellini@xilinx.com>
CommitDate: Tue May 24 16:18:08 2022 -0700
xenstored: send an evtchn notification on introduce_domain
When xs_introduce_domain is called, send out a notification on the
xenstore event channel so that any (dom0less) domain waiting for the
xenstore interface to be ready can continue with the initialization.
Before sending the notification, clear XENSTORE_RECONNECTING.
The extra notification is harmless for domains that don't require it.
In xs_wire.h update the commment on top of XENSTORE_RECONNECTING to
generalize its meaning to suit the dom0less use-case better. Also
improve docs/misc/xenstore-ring.txt.
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
---
docs/misc/xenstore-ring.txt | 8 +++++++-
tools/xenstore/xenstored_domain.c | 4 ++++
xen/include/public/io/xs_wire.h | 2 +-
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/docs/misc/xenstore-ring.txt b/docs/misc/xenstore-ring.txt
index b338b21b19..f3d6ca4264 100644
--- a/docs/misc/xenstore-ring.txt
+++ b/docs/misc/xenstore-ring.txt
@@ -111,7 +111,13 @@ Assuming the server has advertised the feature, the guest can initiate
a reconnection by setting the the Connection state to 1 ("Ring close
and reconnect is in progress") and signalling the event channel.
The guest must now ignore all fields except the Connection state and
-wait for it to be set to 0 ("Ring is connected")
+wait for it to be set to 0 ("Ring is connected").
+
+In certain circumstances (e.g. dom0less guests with PV drivers support)
+it is possible for the guest to find the Connection state already set to
+1 by someone else during xenstore initialization. In that case, like in
+the previous case, the guest must ignore all fields except the
+Connection state and wait for it to be set to 0 before proceeding.
The server will guarantee to
diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index 80ba1d627b..de88bf2a68 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -493,6 +493,10 @@ static struct domain *introduce_domain(const void *ctx,
/* Now domain belongs to its connection. */
talloc_steal(domain->conn, domain);
+ /* Notify the domain that xenstore is available */
+ interface->connection = XENSTORE_CONNECTED;
+ xenevtchn_notify(xce_handle, domain->port);
+
if (!is_master_domain && !restore)
fire_watches(NULL, ctx, "@introduceDomain", NULL,
true, NULL);
diff --git a/xen/include/public/io/xs_wire.h b/xen/include/public/io/xs_wire.h
index 953a0050a3..c1ec7c73e3 100644
--- a/xen/include/public/io/xs_wire.h
+++ b/xen/include/public/io/xs_wire.h
@@ -141,7 +141,7 @@ struct xenstore_domain_interface {
/* Valid values for the connection field */
#define XENSTORE_CONNECTED 0 /* the steady-state */
-#define XENSTORE_RECONNECT 1 /* guest has initiated a reconnect */
+#define XENSTORE_RECONNECT 1 /* reconnect in progress */
/* Valid values for the error field */
#define XENSTORE_ERROR_NONE 0 /* No error */
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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